Category: Software Debug and Trace

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.
As part of the Open Compute Project, Microsoft Azure is leading the charge in providing the technical information needed to democratize the server industry. Recently, they put into the public domain the full schematics and board files for an Intel Xeon Scalable Processor (Skylake-EP) server design. Reviewing the schematics provides great insight into the hardware design implementation needed to support at-scale debug via embedded JTAG run-control.
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