linux-kernel - RE: [PATCH 2/2] hwmon: (coretemp) Get TjMax value from MSR

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Date:	Mon, 30 Aug 2010 09:42:36 +0800
From:	Huaxu Wan <huaxu.wan@...ux.intel.com>
To:	Maxim Levitsky <maximlevitsky@...il.com>,
	Fenghua Yu <fenghua.yu@...el.com>
Cc:	"Wan, Huaxu" <huaxu.wan@...el.com>,
	"'linux-kernel@...r.kernel.org'" <linux-kernel@...r.kernel.org>,
	"'lm-sensors@...sensors.org'" <lm-sensors@...sensors.org>,
	"'khali@...ux-fr.org'" <khali@...ux-fr.org>
Subject: RE: [PATCH 2/2] hwmon: (coretemp) Get TjMax value from MSR

CC Fenghua. 

Could you found a Laptop with T5450 at hand? I can't found anywhere.

-Huaxu

On Mon, 2010-07-26 at 11:16 +0300, Maxim Levitsky wrote:
> On Sun, 2010-06-13 at 10:27 +0800, Wan, Huaxu wrote: 
> > >On Wed, 2010-06-02 at 23:10 +0300, Maxim Levitsky wrote: 
> > >> On Wed, 2010-06-02 at 19:34 +0300, Maxim Levitsky wrote: 
> > >> > On Mon, 2010-05-31 at 09:39 +0800, Huaxu Wan wrote: 
> > >> > > On 08:39 Sat 29 May, Maxim Levitsky wrote:
> > >> > > > On Fri, 2010-05-07 at 17:59 +0800, Huaxu Wan wrote: 
> > >> > > > > The MSR IA32_TEMPERATURE_TARGET contains the TjMax 
> > >value in the newer
> > >> > > > > processers.
> > >> > > > 
> > >> > > > I know that TjMax on my system is 85, and now coretemp 
> > >reports wrong
> > >> > > > temperatures.
> > >> > > > First of all BIOS using stupid tricks actualy reports 
> > >CPU temperature
> > >> > > > through ACPI, and assuming it was correct TjMax is 85.
> > >> > > > It also shuts down the system if I 'lie' to it that 
> > >cpu temperature is
> > >> > > > 85C.
> > >> > > 
> > >> > > From the list at [1], the TjMax(Tjunction) of T5450 is 
> > >100C. Does anyone
> > >> > > here can make a double check?
> > >> > > 
> > >> > > [1] 
> > >http://ark.intel.com/Product.aspx?id=30787&processor=T5450&spec
> > >-codes=SLA4F
> > >> > 
> > >> > This is very interesting.
> > >> > 
> > >> > With TjMax 85C, the CPUs idle temperature is reported at 
> > >around 45~50C
> > >> > GPU temperature that is around 50C 
> > >> > 
> > >> > BIOS also reports 45~50C.
> > >> > 
> > >> > BIOS hooks an SMI to CPU thermal report, and stores the 
> > >temperature it
> > >> > read in ram, then ACPI code reads it, reports and passes to the EC
> > >> > (embedded controller).
> > >> > 
> > >> > If I write myself 85 to embedded controller, systems shuts down.
> > >> > (values less that 85, eg 84 don't shut system).
> > >> 
> > >> 
> > >> Another clue is that right after resume from ram, after long delay
> > >> (~hour) the displayed temperature with TjMax 85 is 33C. Since room
> > >> temperature here is around 27C, this seems more plausible that 
> > >> 33 + 15 = 48C 
> > >
> > >
> > >Any update? 
> > 
> > I'm occupied by other things, sorry for slow response. But, as said in a 
> > spec, I can't remember which one now, there are too many, the relative
> > value read from DTS is accurate approaching to TjMax. The accuracy
> > deteriorates to +-10C at 50C. Any DTS reading below 50C should be
> > considered to indicate only a temperature below 50C and not a specific
> > temperature.
> > 
> > So, the value around 50C can't be taken as real chip temperature. I
> > would like this issue could be confirmed by more users to avoid it as a 
> > particular case. At the meantime, I still looking for a laptop with T5450, 
> > this may take some time. 
> > 
> > Thanks
> > Huaxu 
> 
> Any update?
> 
> Best regards,
> Maxim Levitsky
> 


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