[LinuxBIOS] Thermal monitoring of Pentium 4s

Ronald G. Minnich rminnich at lanl.gov
Wed Jul 27 21:11:06 CEST 2005

On Wed, 27 Jul 2005, Steven J. Magnani wrote:

> I have been looking into some thermal shutdown issues with our board,
> and discovered that LinuxBIOS is not enabling the P4's ability to
> throttle back when the internal sensors indicate that the processor is
> getting too hot.

yes, this is purposeful. We let linux do that here. It is a bad deal if 1 
node of 1022 decides to slow down. 

We do this type of thing in Linux. See the LLNL p4therm module for a piece 
of kernel code that can let you talk to the hardware. 

I think Intel's emphasis on having the BIOS do this kind of thing is a 
real mistake.

> It would be relatively easy to implement support for "TM1" thermal
> control, since that's just setting a MSR bit if the proper CPUID flag is
> set. "TM2" control would be a little more complicated, since there is
> the added ability to control the operating frequency and voltage when
> the processor trips into thermal management mode.

It's easy, and the kernel (directed by a user-mode program) should do it.


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