On Wed, Mar 16, 2016 at 07:44:33PM +0000, Dietmar Eggemann wrote: > intel_pstate (setpolicy()) is an exception but my humble guess is that > systems with intel_pstate driver have X86_FEATURE_APERFMPERF support.
A quick browse of the Intel SDM says you're right. It looks like everything after Pentium-M; so Core-Solo/Core-Duo and onwards have APERF/MPERF. And it looks like P6 class systems didn't have DVFS support at all, which basically leaves P4 and Pentium-M as the only chips to have DVFS support lacking APERF/MPERF. And while I haven't got any P4 based space heaters left, I might still have a Pentium-M class laptop somewhere (if it still boots).
