[Bug 236513] Different power states (C1/C2/...) per CPU core

bugzilla-noreply at freebsd.org bugzilla-noreply at freebsd.org
Wed Mar 13 20:03:26 UTC 2019


--- Comment #1 from Conrad Meyer <cem at freebsd.org> ---
This is a Jaguar-class (Family 16h) AMD CPU.

This information is probed automatically out of the ACPI information presented
by your BIOS.  That code hasn't changed appreciably in 4 years.  It seems your
BIOS does not provide a _CST for all 4 cores, or it is invalid.

Do you see any logs in dmesg about "skipping invalid Cx state" or similar?

Ah, it might be possible that your CPU is new enough to define the cores as
Device objects rather than Processor, but you're running too old of FreeBSD to
enumerate the Device objects and find appropriate C-states _CST tables?  I
don't know if r326956 has been MFCed to 11.x, but that change may address the

Early AP startup (present in 12.0, I think) may also affect this, but I'm not

C-state enumeration on Family 17h AMD CPUs seems to work just fine on CURRENT.

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