New AMD HSMP Driver Features Prepared Ahead Of Zen 4 EPYC

Merged in Linux 5.18 is the AMD HSMP driver for enabling the "Host System Management Port" usage under Linux as an interface for enabling additional system management functionality on AMD EPYC 7003 servers. For Linux 5.19 this AMD HSMP driver is set to be extended with additional features coming with next-generation AMD EPYC servers.

The AMD HSMP Linux driver in conjunction with current-generation AMD EPYC "Milan" processors allow for reading the current average socket power consumption, setting socket power limits, getting/setting maximum frequency limits, min/max width for xGMI links, reading the memory clocks, reading the average C0 residency, and other similar functionality.

A patch from AMD now under review for the amd_hsmp driver within the x86-platform-drivers area is enabling HSMP protocol version 5 support. AMD HSMP protocol version 5 is coming with AMD Family 19h Model 10h EPYC processors, expected to be Zen 4 / EPYC 7004 series based on all the 10h series patches we've seen in recent months.

Added with this new protocol version is support for DIMM statistics like per-DIMM power consumption and temperatures, bandwidth for I/O and xGMI links, setting of power efficiency modes, and other new features.

The AMD HSMP protocol v5 patch can be found here as it undergoes review and given the timing should ultimately find its way into the Linux 5.19 kernel.