Nehalem and older doesn't use the `intel_pstate` driver, but only `acpi-cpufreq`. Thus _CST generation is important for such older platforms.Patrick Rudolph
Is this with current coreboot main branch? It says `intel_pstate: CPU model not supported` and on main there are no ACPI tables containing _CST. So C-states should not work at all. I've written https://review.coreboot.org/c/coreboot/...Patrick Rudolph
Are C-states properly working? If not that would explain high temperature and non working turbo mode. Can you please share full coreboot + kernel log? What does powertop say? Does the CPU enter C1-C7 states? Looking at the code I ...Patrick Rudolph
Likely yes, but BIOS_RESET_CPL can only be set after several MSRs / registers have been written, so enabling it earlier is not possible.Patrick Rudolph
"mwait" is working when you execute the monitor instruction first. It doesn't work without monitor, even when you not want to use it and just want the core to enter C-state. Tested C1 and C3, but turbo is still not working within coreboot.Patrick Rudolph
Observations showed that in coreboot: - C-States are not working (asm("mwait"); has no effect) - Turbo states (core above P0 frequency) aren't working The P-state can be changed after BIOS_RESET_CPL, but it never goes into turbo mod...Patrick Rudolph