[LinuxBIOS] Thermal monitoring of Pentium 4s

[Steven J. Magnani]

Ronald G. Minnich writes:
> the kernel (directed by a user-mode program) should do it.

Ahh, but if the payload is memtest86, there IS no kernel. And that's
where we're having serious shutdown issues.

> See the LLNL p4therm module for a piece of kernel code that can let
you talk to the hardware.

All I can determine from the internet is that this magical piece of
software handles Xeon thermal management. I can't see any links to
source code.

I would argue that since this is a lurking "feature" of LinuxBIOS (you
have to know about it to avoid being bitten, and have to actively do
something in the kernel to avoid thermal issues) that having LB enable
thermal monitoring should be configurable. That would solve both our
issues.

Steve

-----Original Message-----
From: Ronald G. Minnich [mailto:rminnich at lanl.gov] 
Sent: Wednesday, July 27, 2005 1:11 PM
To: Steven J. Magnani
Cc: linuxbios at openbios.org
Subject: Re: [LinuxBIOS] Thermal monitoring of Pentium 4s




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.

ron