Re: Not able to use HIGH_RES_TIMERS on ARM

Re: Not able to use HIGH_RES_TIMERS on ARM

[Ajeet Yadav]

CCing to stable@vger.kernel.org
On Fri, Mar 23, 2012 at 8:58 AM, John Stultz <john.stultz@linaro.org> wrote:
> On 03/22/2012 03:25 AM, Ajeet Yadav wrote:
>>
>> If I set  ARCH_USES_GETTIMEOFFSET=n to use this feature, my target
>> fail to boot. (reason I well understand from our past discussions)
>
> And this point I'm not sure I'm following. Why exactly does disabling
> ARCH_USES_GETTIMEOFFSET cause boot failures? Could you expand on the details
> here?
We did some dissection to narrow down the patch, our latest kernel is
stable 3.0.X , however we backported patch " ARM: 7321/1: cache-v7:
Disable preemption when reading CCSIDR" from 3.0.25 stable tree, this
patch causes kernel hang during boot (IRQSOFF_TRACER=y and
PREEMPT_TRACER=y) with 100% probability , if we remove this patch or
disable the given CONFIG's then boot is success.
>
> You should just end up using the jiffies clocksource, which would give you
> low-res HZ granular timestamps, but shouldn't get in the way of booting.
>
> thanks
> -john
>

Re: Not able to use HIGH_RES_TIMERS on ARM

[Rabin Vincent]

On Fri, Mar 23, 2012 at 11:22, Ajeet Yadav <ajeet.yadav.77@gmail.com> wrote:
> We did some dissection to narrow down the patch, our latest kernel is
> stable 3.0.X , however we backported patch " ARM: 7321/1: cache-v7:
> Disable preemption when reading CCSIDR" from 3.0.25 stable tree, this
> patch causes kernel hang during boot (IRQSOFF_TRACER=y and
> PREEMPT_TRACER=y) with 100% probability , if we remove this patch or
> disable the given CONFIG's then boot is success.

8e43a905dd574f54c5715d9783 ("ARM: 7325/1: fix v7 boot with lockdep
enabled") fixes 7321/1's boot problems.

Re: Not able to use HIGH_RES_TIMERS on ARM

[Ajeet Yadav]

On Fri, Mar 23, 2012 at 11:47 AM, Rabin Vincent <rabin@rab.in> wrote:
> On Fri, Mar 23, 2012 at 11:22, Ajeet Yadav <ajeet.yadav.77@gmail.com> wrote:
>> We did some dissection to narrow down the patch, our latest kernel is
>> stable 3.0.X , however we backported patch " ARM: 7321/1: cache-v7:
>> Disable preemption when reading CCSIDR" from 3.0.25 stable tree, this
>> patch causes kernel hang during boot (IRQSOFF_TRACER=y and
>> PREEMPT_TRACER=y) with 100% probability , if we remove this patch or
>> disable the given CONFIG's then boot is success.
>
> 8e43a905dd574f54c5715d9783 ("ARM: 7325/1: fix v7 boot with lockdep
> enabled") fixes 7321/1's boot problems.
Hi Rabin,
Thanks for fixing the boot problem, we have tested it, fixed.

Re: Not able to use HIGH_RES_TIMERS on ARM

[Greg KH]

On Fri, Mar 23, 2012 at 11:22:46AM +0530, Ajeet Yadav wrote:
> CCing to stable@vger.kernel.org

Why?  What am I supposed to do here?

confused,

greg k-h

Re: Not able to use HIGH_RES_TIMERS on ARM

[Ajeet Yadav]

I send earlier reply using my andriod gmail application, and it was
rejected by stable/ linux-kernel (not in plain text), so sending again
using PC.

On Fri, Mar 23, 2012 at 9:44 PM, Greg KH <greg@kroah.com> wrote:
> On Fri, Mar 23, 2012 at 11:22:46AM +0530, Ajeet Yadav wrote:
>> CCing to stable@vger.kernel.org
>
> Why?  What am I supposed to do here?
>
> confused,
>
> greg k-h
I initially thought that problem is in 3.0.x stable, but I was wrong.
Solution patch suggested by Rabin is already there in stable.
Summary:
" ARM: 7321/1: cache-v7: > Disable preemption when reading CCSIDR"
introduce hang on boot, that is resolved by commit

"ARM: 7325/1: fix v7 boot with lockdep enabled"
 fortunately both are in 3.0.x so no problem,

but i do not know about other stable versions.