> not sure that powertop performs any specific MSRs at all, since most of MSRs are
> called correspondingly to c-state flags (has_cXXX), e.g.
>
> __init:
> 	if (model == 0x45 || model ==0x3D)
> 		has_c8c9c10_res = 1;
>
>
>
> and later:
>
> 	if (has_c8c9c10_res) {
> 		c8_before    = get_msr(number, MSR_PKG_C8_RESIDENCY);
> 		c9_before    = get_msr(number, MSR_PKG_C9_RESIDENCY);
> 		c10_before    = get_msr(number, MSR_PKG_C10_RESIDENCY);
> 	}
>
> 	and so on.


but if the set is empty, you don't get any data, and the "emulation" side of powertop
is likely a better choice... since there are C states, just not counters.