Comment 62 for bug 1983180

(In reply to Takehiko Abe from comment #57)
> "Enable/Disable Intel Speed Shift Technology support. Enabling will expose
> the CPPC v2 interface to allow for hardware controlled P-sates."
>
> When I first got the error messages with 5.12.6 last year, I confirmed that
> the error messages disappears with CPPC v2 option disabled. But disabling
> CPPC v2 support is not a way to go, I guess?
>
> I believe ASRock B460M also supports CPPCv2.

I mentioned the same observation in Bug 216070 that acpi_cppc interface is gone. I just looked my ASRock B460M-ITX's firmware settings. You are right, the option "Enable/Disable Intel Speed Shift Technology support" has the same help message.

But I don't know if the bug / current fix disables any function that had worked before. Based on various online resources, my understanding is "Intel Speed Shift" = HWP (Hardware P-state) in Linux, and I can see kernel message say it always works (intel_pstate: HWP enabled).

(In reply to Mario Limonciello (AMD) from comment #58)
> Are you sure it actually worked before? The firmware masking it does not
> give me confidence it really worked.

I can confirm /sys/devices/system/cpu/cpuX/acpi_cppc/ exists before 5.17.2 when the error hadn't been introduced. But I don't know if things in it were actually usable. Is there anything I can do to test if CPPCv2 works on old kernels?