[lm-sensors] [PATCH 2/2] hwmon: (coretemp) Get TjMax value from MSR

Maxim Levitsky maximlevitsky at gmail.com
Sat Jun 12 15:03:59 CEST 2010


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 60C
> > 
> > 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? 
> 
> 
> Best regards,
> Maxim Levitsky
> 






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