AMD has published a new set of patches for the Linux kernel that add support for the AMD Overclocking Driver, known as AOD, on Ryzen processors. Phoronix reported the submission, which gives Linux users an officially backed route to CPU tuning features that Windows users have long had through Ryzen Master.
Until now, Linux users who wanted to adjust Ryzen behavior have largely had to work through UEFI/BIOS firmware settings. The new driver is meant to change that by providing a direct channel to AMD's platform adjustments, sparing developers from reverse-engineering closed-source firmware hooks or relying on machine-specific ACPI workarounds.
The driver presents its controls through the standard sysfs interface, giving software-level CPU management an official, upstreamed foundation. In its first form, it covers platform-level toggling of Simultaneous Multithreading (SMT), visibility into memory clocks, and a set of power tunables.
The SMT control works through the CPU hotplugging mechanism. It can be changed dynamically and offers a cleaner alternative to passing the older 'nosmt' boot parameter to the kernel. The driver also allows real-time monitoring of memory clocks, and initial power controls are in the process of being wired up.
Users hoping for a polished, one-click AMD application on the order of Ryzen Master will not get one from this release. AMD is following the approach it has taken with its open-source amdgpu graphics driver: it builds the kernel-level plumbing and leaves the user-space presentation layer to the community.
That means graphical tools such as CoreCtrl will need to add interfaces for the new driver. The source suggests that work should begin in earnest before long.
The approach is arguably a good match for the Linux philosophy. Because the controls are exposed as sysfs nodes, independent developers can fold them into open-source monitoring and tuning suites, or write desktop environment extensions aimed specifically at adjusting Ryzen processors.
The patches are currently going through review on the kernel mailing lists, so inclusion in the mainline kernel appears to be on the horizon. For enthusiasts who want to squeeze every last MHz out of their silicon while keeping a fully open-source software stack, Tom's Hardware's writer called it easily the most exciting hardware-enablement milestone in a long time.
