Serial Link Sideband Debug Messaging for In-Situ Failure Diagnosis

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Solution Overview

Problem

Current debug techniques for serial links like USB4 and Thunderbolt are inadequate for root-causing hard failures and often require reworking customer boards, which is risky and disruptive, while existing logic analyzers fail to accurately diagnose non-link related failures.

Innovation Solution

A Debug Type Messaging (DTM) protocol is implemented using the sideband channel of serial links to probe components in-situ without disrupting primary traffic, allowing for non-invasive debugging of link and IP failures through a state-less, best-effort delivery protocol.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Difficulty of detecting and measuring

If rework is performed to expose JTAG pins for debugging hard link failures, then access to component registers is achieved, but board survivability drops below 100% and debugging becomes disruptive

Engineering Contradiction:

Improveaccess to component registersVSAvoidboard survivability

Core Design Contradiction:

Difficulty of detecting and measuringVSReliability

Solution Approach 1:

The patent introduces an intermediary debug interface that provides indirect access to component registers without requiring physical board rework. This intermediary mechanism allows debugging while preserving board integrity, resolving the contradiction between accessing registers and maintaining board survivability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the debugging function from the primary board structure by providing a separate access path to component registers. This segmentation allows debugging operations to occur independently without affecting the overall board integrity and survivability.

Inventive Principle:

Principle #1Segmentation

2Difficulty of detecting and measuring

If a primary interface is used to debug faulty IP, then debugging capability is provided, but the interface introduces perturbation that distorts failure signatures

Engineering Contradiction:

Improvedebugging capabilityVSAvoidfailure signature accuracy

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent introduces a dedicated debug interface as an intermediary that provides clean access to component registers without introducing the perturbation and distortion that occurs when using the primary interface. This intermediary path preserves the integrity of failure signatures while enabling debugging capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of information

If USB4/TBT3 logic analyzers are used to analyze protocol failures, then protocol-level analysis is achieved, but root-cause analysis of hard failures becomes impossible

Engineering Contradiction:

Improveprotocol failure analysisVSAvoidhard failure root-cause access

Core Design Contradiction:

Loss of informationVSDifficulty of detecting and measuring

Solution Approach 1:

The patent merges the capabilities of protocol-level analysis with direct hardware access by providing a unified debug interface that can access component registers. This combination enables both protocol failure analysis and hard failure root-cause analysis through the same interface, eliminating the limitation of logic analyzers.

Inventive Principle:

Principle #5Merging (Combining)

4Difficulty of detecting and measuring

If special debug mode is entered to access components, then component access is enabled, but primary traffic is disrupted

Engineering Contradiction:

Improvecomponent accessVSAvoidprimary traffic flow

Core Design Contradiction:

Difficulty of detecting and measuringVSProductivity

Solution Approach 1:

The patent segments the debug access path from the primary traffic path, allowing component access through a separate interface that does not interfere with or disrupt primary traffic flow. This segmentation enables simultaneous operation of debugging and normal traffic handling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary debug interface that mediates access to components without requiring the system to enter a special debug mode that would disrupt primary traffic. This intermediary provides a parallel path for debugging that leaves primary operations undisturbed.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12392824B2System, apparatus and method for communicating debug messages on a sideband of a serial link according to a debug type messaging protocol

Publication Date: 2025.08.19 INTEL CORP

AI summary

In one embodiment, a method includes: in response to identifying an error in a device of a computing environment coupled to a host system of the computing environment via a serial link, sending, from a requester, a debug type messaging (DTM) request towards the device via a sideband portion of the serial link, the requester in-situ to the computing environment; and receiving, in the requester, a DTM response to the DTM request, the DTM response including status information of the device, via the sideband portion of the serial link. Other embodiments are described and claimed.