[LinuxBIOS] AMD Geode LX support for LinuxBIOS

[Marc Jones]

Carl-Daniel Hailfinger wrote:
> On 03.05.2007 19:17, Stefan Reinauer wrote:
>> * Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net> [070503 19:16]:
>>> The concept of code not under the control of the operating system is
>>> frightening some low-latency audio/video folks. If the operating system
>>> uses some operations heavily which trigger SMM execution, extended
>>> periods of switched off interrupts may result.
>> Yes, anyone doing real time systems has a problem with this. 
>>
>>> OTOH, systems which need SMM should probably not be used anyway if
>>> latency is critical.
>> They can not. This is the reason a lot of people are using LinuxBIOS
>> rather than legacy bios.
> 
> How do we deal with fan control, then? Most recent mainboards use
> SMM for fan control. Once you forbid SMM, you have to trust the OS
> to perform fan control correctly, which will fail if the machine
> crashes or locks up.
> 
> Regards,
> Carl-Daniel

In the legacy/APM world power management and fan control were mostly 
done in SMM.

In the ACPI world that has been moved to the OS. Proper drivers and 
applications and SMM all play a part but SMM's role is greatly reduced 
and latency much less of an issue. You might also want to look at the 
OpenIPMI project to see how some of this is being done now.
http://openipmi.sourceforge.net/IPMI.pdf

Marc





-- 
Marc Jones
Senior Software Engineer
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mailto:Marc.Jones at amd.com
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