Category: Embedded Diagnostics

ASSET implements in-situ diagnostics via direct support of the x86 JTAG-based run-control API down on the target. The run-control API are synonymous with lower-level Intel In-Target Probe (ITP) procedures. What follows is a sample ‘C’ routine written to dump the contents of the machine check registers, in the event of a system wedge (for example, a three-strike event).
Moving run-control (Intel In-Target Probe, or ITP) down into the service processor on an x86 design results in a screamingly fast, scalable implementation of at-scale debug. This article contains some timing benchmarks of our embedded solution versus alternatives. The results are nothing short of astonishing.
Embedding JTAG into a system’s service processor allows for powerful out-of-band (independent of the operating system) built-in self test (BIST) functions. Using JTAG-based boundary scan, for example, can isolate system failure root cause to an extent unachievable through any other means.
High-end, mission-critical systems often use a plethora of diagnostic routines for power-on self test (POST), data logging, operational measurements, Built-In Self Test (BIST), and platform audits. Embedded x86 JTAG run-control adds out-of-band services to this mix. This article describes one such use case for Power-On Self Test (POST) of PCI Express ports.
In the article JTAG and run-control API in BMCs for at-scale debug, I described how embedding the Intel ITP run-control library down on a service processor provides for a rich set of target-based functions for debug forensics. How might this apply to reading MSRs, such as the ones created to address Spectre and Meltdown.
In my last article, I described how the Open Compute Project (OCP) Project Olympus server designs have been put into the public domain by Microsoft Azure. Inherent in the Olympus servers is the hardware connection between the ASPEED BMC and the CPU JTAG chain. To make the most of this connection for hardware-assisted debug and test purposes, a high-performance, secure JTAG Master function is needed within the BMC.