CXL DUT Testing With Isolated Memory and Managed Hot Add
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Solution Overview
Problem
Existing testing systems and methods for Compute Express Link (CXL) protocol compliant devices face challenges such as shared memory interference, inability to hot add or swap devices without rebooting, and inefficient parallel testing, leading to unreliable results and resource wastage.
Innovation Solution
A system and method that enables managed hot add and swap of CXL devices without rebooting, using a user interface and tester to suspend testing, perform enumeration transparently, and utilize Direct Access Device (DAX) interfaces to isolate memory, allowing parallel testing with independent workloads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CXL DUTs operate in shared system memory mode, then memory resources are efficiently utilized, but memory interference and corruption occur between devices
Solution Approach 1:
The patent segments the shared system memory space into isolated device memory spaces for each CXL DUT. Each device is assigned its own memory region with dedicated access controls, preventing one device from accessing or corrupting another device's memory while maintaining efficient resource utilization through the shared CXL interface.
2Measurement precision
If CXL devices require BIOS initialization for enumeration, then device recognition is thorough, but hot add capability is lost requiring system reboots
Solution Approach 1:
The patent implements preliminary device enumeration and configuration capabilities that allow CXL devices to be recognized and initialized without requiring a full BIOS reboot. The system performs preliminary checks and registrations of new devices through the CXL interface, enabling hot add functionality while maintaining accurate device enumeration through pre-configured enumeration protocols.
3Adaptability or versatility
If traditional test systems shut down to add/swap CXL devices, then device changes are implemented, but testing time and resources are wasted
Solution Approach 1:
The patent enables continuous testing operations by allowing CXL devices to be added, removed, or swapped without shutting down the test system. The testing process maintains continuity through persistent test state storage and automatic resumption capabilities, eliminating downtime and resource waste associated with traditional shutdown-required device changes.
4Productivity
If multiple CXL DUTs are tested in parallel without isolation, then testing throughput increases, but test interference and unreliable results occur
Solution Approach 1:
The patent segments the test environment into isolated test spaces for each CXL DUT, with dedicated test protocols and memory access controls. This segmentation allows multiple devices to be tested in parallel with independent test sequences, maintaining high throughput while preventing test interference through strict isolation boundaries and dedicated test resources for each device.
Data Source
AI summary
Efficient and effective testing systems and methods are presented. In one embodiment, a system includes: a user interface configured to enable user interaction with the system; a test board configured to communicatively couple with a plurality of devices under test (DUTs), wherein the DUTs are compute express link (CXL) protocol compliant; and a tester configured to direct testing of the plurality of DUTs, wherein the tester is configured to enable hot add of one of the plurality of DUTs without interfering with testing of the other DUTS. In one exemplary implementation, the DUTs are memory devices and the DUTs can operate as extended memory. An added DUT can be automatically recognized by a host in a way that is transparent to users (e.g., BIOS can direct detection of characteristics of an added DUT, etc.). The tester automatically can direct the hot add in response to a user trigger.