# ACPI C2/C3 support for AMD E350



## c_geier (Aug 25, 2012)

Hi,
I have an Asus e35m1-m pro board running FreeBSD 9.0. And it looks like it only supports C2 on one of the two cores and C1 on the other.


```
hw.acpi.cpu.cx_lowest: C2
dev.cpu.0.cx_supported: C1/0 C2/100
dev.cpu.0.cx_lowest: C2
dev.cpu.0.cx_usage: 0.31% 99.68% last 912us
dev.cpu.1.cx_supported: C1/0
dev.cpu.1.cx_lowest: C1
dev.cpu.1.cx_usage: 100.00% last 969us
```


Does anybody know if either 9.1 or 10 would at least support C2 on both cores or preferably even c3?

Thanks


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## mav@ (Aug 25, 2012)

1. It is the first case I see AMD systems to report C-states. Why it is only on one CPU is good question.
2. These C-state numbers have nothing to do with CPU C-states. They are just sequentially numbered here.


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## c_geier (Aug 26, 2012)

mav@ said:
			
		

> 2. These C-state numbers have nothing to do with CPU C-states. They are just sequentially numbered here.



So what do these C-state numbers mean?


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## mav@ (Aug 27, 2012)

c_geier said:
			
		

> So what do these C-state numbers mean?



You should separate CPU C-states and ACPI C-states. CPU C-states are vendor- or even model-specific. ACPI C-states have three different types 1, 2 and 3 that mean: 1 - stop some clocks, 2 - stop most of clocks, 3 - stop all clocks, save state and power-down. But ACPI C-state types are not directly mapped into C-state numbers. For example, CPU may have one state of type 1 and two states of type 3. FreeBSD just numbers ACPI C-states sequentially in order of decreasing power consumption, so these numbers don't mean anything specific.


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