On Wed, 28 Oct 2020, David E. Box wrote: > Intel Platform Monitoring Technology (PMT) is an architecture for > enumerating and accessing hardware monitoring capabilities on a device. > With customers increasingly asking for hardware telemetry, engineers not > only have to figure out how to measure and collect data, but also how to > deliver it and make it discoverable. The latter may be through some device > specific method requiring device specific tools to collect the data. This > in turn requires customers to manage a suite of different tools in order to > collect the differing assortment of monitoring data on their systems. Even > when such information can be provided in kernel drivers, they may require > constant maintenance to update register mappings as they change with > firmware updates and new versions of hardware. PMT provides a solution for > discovering and reading telemetry from a device through a hardware agnostic > framework that allows for updates to systems without requiring patches to > the kernel or software tools. > > PMT defines several capabilities to support collecting monitoring data from > hardware. All are discoverable as separate instances of the PCIE Designated > Vendor extended capability (DVSEC) with the Intel vendor code. The DVSEC ID > field uniquely identifies the capability. Each DVSEC also provides a BAR > offset to a header that defines capability-specific attributes, including > GUID, feature type, offset and length, as well as configuration settings > where applicable. The GUID uniquely identifies the register space of any > monitor data exposed by the capability. The GUID is associated with an XML > file from the vendor that describes the mapping of the register space along > with properties of the monitor data. This allows vendors to perform > firmware updates that can change the mapping (e.g. add new metrics) without > requiring any changes to drivers or software tools. The new mapping is > confirmed by an updated GUID, read from the hardware, which software uses > with a new XML. > > The current capabilities defined by PMT are Telemetry, Watcher, and > Crashlog. The Telemetry capability provides access to a continuous block > of read only data. The Watcher capability provides access to hardware > sampling and tracing features. Crashlog provides access to device crash > dumps. While there is some relationship between capabilities (Watcher can > be configured to sample from the Telemetry data set) each exists as stand > alone features with no dependency on any other. The design therefore splits > them into individual, capability specific drivers. MFD is used to create > platform devices for each capability so that they may be managed by their > own driver. The PMT architecture is (for the most part) agnostic to the > type of device it can collect from. Software can determine which devices > support a PMT feature by searching through each device node entry in the > sysfs class folder. It can additionally determine if a particular device > supports a PMT feature by checking for a PMT class folder in the device > folder. > > This patch set provides support for the PMT framework, along with support > for Telemetry on Tiger Lake. > > Changes from V8: > - Rebase on 5.10-rc1 > - Add missing changes in MFD patch from V7 that were accidentally > dropped in V8 Which changes are those? Do I need to re-review? > - Remove error message when unsupported capability found. Avoids > unnecessary noise on some systems. -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog
