U.2 NVMe Hot-Unplug Detection for PCIe Timeout Prevention
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Solution Overview
Problem
The PCIe 3.0 norm in server systems fails to process unfinished IO requests during a brute force hot unplug of U.2 NVMe solid-state disks, leading to processor waiting timeout errors and system crashes.
Innovation Solution
A method and apparatus that utilize a predefined short signal pin to detect the presence of the NVMe solid-state disk, triggering a System Management Interrupt (SMI) program to break the link between the PCIe root bridge and the disk before the long signal pin disconnects, thereby preventing the processing of unfinished IO requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If PCIe 3.0 norm is used for brute force hot unplug operation, then the operation conforms to user habits and is simple to execute, but unfinished IO requests cannot be processed causing processor waiting timeout errors and system crashes
Solution Approach 1:
The patent applies preliminary action by detecting the unplug state through GPIO input state changes before the PCIe link is fully broken. The SMI program is triggered in advance to handle unfinished IO requests, preventing processor timeout errors. This allows the brute force hot unplug operation to proceed while maintaining system stability through proactive intervention.
2Ease of operation
If brute force hot unplug is performed without notifying driver in advance, then the operation is simple and matches user habits, but processor waiting timeout errors occur due to unfinished IO requests
Solution Approach 1:
The patent introduces an intermediary mechanism - the SMI program triggered by GPIO state changes - that mediates between the brute force hot unplug operation and the PCIe link. This intermediary detects the unplug event and processes unfinished IO requests before the link is broken, eliminating processor timeout errors while maintaining the simplicity of the hot unplug operation.
3Speed
If link between PCIe root bridge and NVMe solid-state disk is broken immediately during hot unplug, then the unplug operation is fast, but unfinished IO requests cause system crashes
Solution Approach 1:
The patent applies preliminary action by triggering the SMI program through GPIO state detection before the PCIe link is fully broken. This allows the system to process unfinished IO requests in advance, maintaining system stability while enabling fast hot unplug operation. The link is broken quickly after the preliminary processing is complete.
Data Source
AI summary
The present application discloses a processing method for a brute force hot unplug operation on a U.2 NVMe solid-state disk, including: predefining a short signal pin for detecting whether an NVMe solid-state disk is in place; presetting to trigger an operation of calling a SMI program according to input state change information of GPIO of a PCH chip, where an input state value of the GPIO is determined according to a connection state of the short signal pin and a U.2 slot; calling the SMI program when a change in an input state of the GPIO is detected, and reading the input state value of the GPIO; and breaking a link between a PCIe root bridge and the NVMe solid-state disk by using the SMI program if the input state value of the GPIO is a corresponding value about the NVMe solid-state disk not in place.