Driver Tracing Interface
This paper proposes a driver-tracing interface (DTI) that builds on the existing Relay tool and the proven Debug Feature model used by IBM™ zSeries Linux. Users of this infrastructure are provided with individual, manageable channels for capturing or passing debug data into user space. Separate channels are created by each subsystem or driver. Data is stored in kernel ring buffers providing flight recorder type functionality. Unwanted or unconsumed data is simply discarded where pertinent data can be saved for future analysis. In the instance of a system crash, all unconsumed tracing data is automatically saved in crash dumps. With support from crash analysis tools like crash or lcrash, trace data can be extracted directly from a crash dump, providing an exact trace of the events leading up to the crash.
Developers of Linux™ device drivers will be interested in DTI as a tool to aid in the troubleshooting of their drivers. Service engineers and support personnel who are tasked with isolating driver bugs will learn how to capture DTI data on a live system and extract DTI data from a crash dump.