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Does anyone know why the ACPI namespace keeps changing? I had a script a while back on a Red Hat system which read the CPU temperature from '/proc/acpi/thermal_zone/THRM'. Now I have a new (but similar hardware) and relatively same distro (except for a few drivers here and there) and it has changed to '/proc/acpi/thermal_zone/TZ00' and '/proc/acpi/thermal_zone/TZ01'?

Is this even the CPU thermal? Or is it for something else?

I know most will say, read the ACPI docs... But that's beyond the point. Why and who keeps changing the namespace?

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up vote 4 down vote accepted

ACPI is tied to the hardware which has changed dramatically in the last 15 years. Dual core processors which never existed (or where extremely expensive in '97) are now standard. Modern GPUs are now so power hungry that they may need their own thermal monitors. The cost of adding thermal monitors is now cheap enough other devices may also have thermal monitors.

Don't blame the software people for having to keep up with hardware changes. This is natural. Change can be frustrating. Relax, take ten deep breaths, and adapt if necessary.

Most releases now have a variety of tools to monitor and report temperatures. Many are good at self configuring. You might want to check them out.

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I can appreciate the evolution of changes within the Linux ACPI modules, but I don't understand the naming conventions. Like I said, TZ00 and TZ01 makes no sense to anyone. Given that these are normally 2 degrees Celsius apart, which is the CPU and what in the world could the other be? Valid names like 'core0' or 'cpu0' or 'gpu1' etc would be more informative and logical. Thanks for you response! – Jeach Apr 4 '11 at 16:28
@Jeach: I suspect the names may come from the ACPI interface. This is provided by the manufacturers who usually program to their own specs. I suspect the zones correspond to CPU0 and CPU1. Having looked at an ACPI configuration dump in the past I agree that the names could be better. Some sensors seem to need to be scanned and can be deployed for multiple purposes. These are identified by type, and sensor utilities may have a translation table for your system. Otherwise, the software can only guess by type. – BillThor Apr 4 '11 at 22:25

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