Comment 616 for bug 1690085

(In reply to Klaus Mueller from comment #528)
> What's the downside of generally disabling mwait?

So in your case, you can't do MWAIT to enter C1 anyway because your
revision doesn't support it. This is why you're seeing those firmware
messages.

> I'm using a Ryzen 7 1700X and don't have any problem ("fixed" it w/
> 200 MHz of CPU Overclocking). The only thing I see, is, that the ACPI
> firmware bug messages disappear. That's all.

That's an "interesting" way to fix it but if it works ... :)

The intention of the fix is to make idle=halt the default for obvious reasons.

HTH.