[LinuxBIOS] Thermal monitoring of Pentium 4s

Steven J. Magnani steve at digidescorp.com
Wed Jul 27 20:29:55 CEST 2005

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.

According to the System Programming Guide, Vol. 3 of the IA-32 Intel
Architecture Software Developer's Manual (p. 13-24):

"BIOS is required to enable only one automatic thermal monitoring modes
(sic). Operating systems and applications must not disable the operation
of these mechanisms."

Has this been considered for LB? I didn't see any discussions in the
mailing list archives.

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.


More information about the coreboot mailing list