Missing CPU Power Management Section (2.1.3) in "PPR for AMD Family 17h Models 00h-0Fh"

Discussion created by ucb-cyarp on Oct 19, 2018

Hi Everyone,

I'm new to the forums here so please excuse my ignorance.


I am currently working on a research project utilizing a Ryzen 2990WX.  We are interested in adjusting the voltage levels associated with the different CPU power states and came across the "PStateDef" register in the "PPR for AMD Family 17h Models 00h-0Fh" document.  It looks like the CpuVid field is what we are interested in changing.  However, the register description refers to section 2.1.3 (CPU Power Management) which is empty in the Rev 1.14 (April 15, 2017) version of the document (https://www.amd.com/system/files/TechDocs/54945_PPR_Family_17h_Models_00h-0Fh.pdf from https://developer.amd.com/resources/developer-guides-manuals/).  Does anyone know if there is a new version of this document with section 2.1.3 populated?


On a related note, is there a method besides directly reading/writing the MSR registers that I should be using to adjust the definitions of the different P states (clock rate, voltage, and max current)?  We are currently operating in a Linux (Ubuntu 18.04) environment.