linux-kernel - RE: 2.6.31.4: WARNING: at arch/x86/kernel/hpet.c:390 hpet_next_event+0x70/0x80() [occurs when ACPI

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Date:	Sat, 14 Nov 2009 03:48:48 -0500 (EST)
From:	Justin Piszcz <jpiszcz@...idpixels.com>
To:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
cc:	Thomas Gleixner <tglx@...utronix.de>,
	john stultz <johnstul@...ibm.com>,
	lkml <linux-kernel@...r.kernel.org>,
	Arjan van de Ven <arjan@...radead.org>
Subject: RE: 2.6.31.4: WARNING: at arch/x86/kernel/hpet.c:390
 hpet_next_event+0x70/0x80() [occurs when ACPI_PROCESSOR=y]



On Fri, 13 Nov 2009, Pallipadi, Venkatesh wrote:

> On Fri, 2009-11-13 at 10:43 -0800, Justin Piszcz wrote:
>>
>> On Fri, 13 Nov 2009, Pallipadi, Venkatesh wrote:
>>
>>> On Fri, 2009-11-13 at 01:38 -0800, Thomas Gleixner wrote:
>>>> On Thu, 12 Nov 2009, Pallipadi, Venkatesh wrote:
>>>>> Yes. Yes. This is a hardware errata. I have a patch to workaround this and
>>>>> waiting on the errata description to get published..
>>>>
>>>> Can we at least have some PCI quirk or whatever until you can push the
>>>> final workaround out so peoples machines do not explode ?
>>>
>>> Its a harmless bug functionality-wise and should not have any side
>>> effect other than triggering the WARN_ON_ONCE in hpet next event code.
>>>
>>> Thanks,
>>> Venki
>>>
>>
>> Venki,
>>
>> When the following patch is applied though: (courtesy of john stultz)
>>
>
> Justin,
>
> I am missing something in here.
> Without the below patch, on 2.6.31.4 and ACPI_PROCESSOR loaded (either
> as module or builtin), you may see the WARNING. But, that should not
> cause any other problems with C-states, P-states, or anything else.
> Is that what you are seeing?
>
> The below patch is not a workaround for the problem. Infact it will make
> situation worse with constant stream of prinkts and can reduce the
> C-state residency and turbo upside.
>
> Thanks,
> Venki

Venki,

Without the below patch and ACPI_PROCESSOR loaded:

1. the warning? yes--however..
2. my processor does not enter turbo boost mode without the processor
    module
-
3. the patch shows that the hpet writes are failing-- when the processor
    module is loaded, the cpu/mobo/vrm emits a high-pitch noise-- my guess
    is due to the hpet write failures, failing over and over, this does
    not occur when the processor module is not loaded.

Justin.


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