New silicon features, along with debugger tool features that use them, can make a large difference in the time it takes to find the really hard bugs encountered during each UEFI port. Intel® has recently introduced two very important debug features in its processors. These debug features are (1) Trace Hub, and (2) Intel Processor Trace. Source level debuggers like ASSET InterTech’s SourcePoint™ contain trace features that use these silicon debug hooks to offer some very strong tool elements that have never been found in the Intel environment before.
Every project to port UEFI (the boot code in Intel based computers) to a new motherboard takes many months and is always plagued by at least a few really hard-to-find software bugs. Finding these software bugs can radically extend the project time. Many of these hard bugs have their root-cause based on asynchronous software events, possibly in separate execution environments. Trace is often the only way to directly observe these interactions.
Software bugs will be seen by drilling into instruction trace where the root cause is occurring. That said, finding the place in a massive body of linear trace can be like finding the proverbial needle in a haystack. Trace Hub, Intel’s new feature that includes an implementation of System Trace (STM), can be the tool to find your way around in this huge stack of hay (a linear trace file).
STM allows programmers to instrument their code. While folks have done this for years with printf and logging, STM allows these messages to be integrated into trace streams and time aligned with other trace sources. When used with the correct libraries, STM can also make this instrumentation orders of magnitude more efficient. UEFI code bases all have lots of instrumentation in them already, as do other firmware bodies of code found within Intel processor based systems. These existing instrumentation messages can be easily rerouted to Trace Hub and processed with source level debuggers.
If you are interested in learning more about how Intel’s Trace Hub can be combined with Intel Processor Trace to aid in root-causing those really hard-to-find UEFI bugs, please read our new eBook "Intel's Trace Hub | New Methods for Software Debug Find Root Cause Faster!"