With the upcoming Linux 6.17 kernel cycle Intel is further building out their Platform Monitoring Technology (PMT) capabilities with the introduction of a new discovery driver.
After going through a few rounds of code review on the Linux kernel mailing list, the Intel VSEC/PMT Discovery Driver is expected to be upstreamed for the Linux 6.17 merge window. The patches crossed the milestone of being queued up within the platform-drivers-x86.git’s “for-next” Git branch. With the discovery driver patches making it to that respective “for-next” branch, they are expected to be submitted for the next (Linux 6.17) merge window.
The Intel PMT/VSEC Discovery Driver was explained on the Linux kernel mailing list as:
“This patch series introduces a new discovery driver for Intel Platform Monitoring Technology (PMT) and a set of supporting changes to improve telemetry integration across Intel VSEC features.
The primary goal of this series is to add the PMT Discovery driver, which enumerates and exposes telemetry attributes by parsing hardware-provided discovery tables from OOBMSM devices. In particular, the discovery driver gathers detailed capability information (such as telemetry region attributes) that will later enable direct access to telemetry regions via a new API (intel_pmt_get_regions_by_feature()). This API is crucial for retrieving data like per-RMID counters.
The remainder of the series consists of several preparatory and testing patches:
1. Private Data and CPU Mapping: The VSEC driver now includes per-device private data to store the OOBMSM-to-CPU mapping. The TPMI driver copies its platform info into this common area (via intel_vsec_set_mapping()), allowing other VSEC features to access CPU mapping information without redundant queries.
2. Device Links Enhancements: With telemetry now depending on both the TPMI driver (for CPU mapping) and the new discovery driver (for telemetry region attributes), device links have been added and optimized. These changes ensure that supplier drivers are probed and registered before consumer drivers, enforcing the proper dependency order for reliable telemetry feature access.
4. Discovery Driver and API: The core of the series is the addition of the PMT Discovery driver. This driver not only implements discovery of telemetry attributes and capability data (exposed via sysfs) but also introduces an API to retrieve telemetry regions by feature, which is essential for features like per-RMID telemetry counters.
5. Testing: A simple KUNIT test is provided for the enhanced discovery API to ensure its reliability and correctness.
Together, these patches provide a foundation for future telemetry enhancements in the Intel VSEC framework. They enable a unified interface for accessing hardware telemetry capabilities and ensure that inter-driver dependencies are properly managed through device links.”
The Linux 6.17 merge window is expected to be open by early August while the stable kernel should be out by early October.
