PCI-Express Reset Conversion for Multi-Host Shared I/O Precision
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Solution Overview
Problem
In shared I/O environments, hosts inadvertently reset functions owned by other hosts due to the propagation of reset commands through the PCI hierarchy, causing unintended resets in multi-host setups.
Innovation Solution
Converting in-band hot resets to functional level resets while in transit, allowing hosts to specifically reset only their bound functions without affecting other hosts' functions, using a PCI-Express system with a virtual P2P bridge and switch architecture to manage and route these resets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a host transmits a reset command to a shared I/O device, then the device can be reset, but the reset propagates downstream through the PCI hierarchy and inadvertently resets functions owned by other hosts
Solution Approach 1:
The patent segments the reset operation from the global bus level to the function level. Instead of transmitting a reset command that propagates through the entire PCI hierarchy, the system converts the reset to a function-level operation that only affects the specific function bound to the initiating host. This segmentation isolates the reset effect to the intended target only.
Solution Approach 2:
The patent introduces an intermediary conversion mechanism between the host's reset request and the actual device reset. The system intercepts the reset command, converts it from a bus-level hot reset to a function-level reset, and then applies it only to the bound function. This intermediary process prevents direct propagation to other functions.
2Adaptability or versatility
If multiple hosts share I/O device functions, then resource utilization improves, but reset commands from one host can affect functions bound to other hosts
Solution Approach 1:
The patent applies local quality by making the reset operation function-specific rather than bus-wide. Each function bound to a host receives reset treatment locally and independently. The system identifies which function is bound to which host and applies the reset only to that specific function, creating localized reset effects in a shared environment.
Solution Approach 2:
The patent segments the shared I/O device into individually controllable functions, each with its own reset control. Instead of treating the shared device as a single unit where a reset affects all functions, the system divides reset control into function-level segments, allowing each host to independently reset only its bound function without affecting other hosts.
3Speed
If a hot reset is propagated through the PCI hierarchy, then the reset reaches the peripheral device, but it cannot be prevented from affecting other functions on the same link
Solution Approach 1:
The patent substitutes the mechanical/bus-level hot reset propagation mechanism with a function-level reset mechanism. Instead of relying on the physical propagation of reset signals through the PCI hierarchy which inherently affects all devices on the link, the system uses a converted function-level reset that operates at a higher level of abstraction, achieving precise targeting without physical signal propagation limitations.
Data Source
AI summary
Embodiments include methods, apparatus, and systems for converting resets in a shared I/O system. One embodiment includes a method that propagates a first type of reset from a host computer to a multi-function device that shares I/O operations with other hosts. The first type of reset is converted to a second type of reset to prevent the host from resetting functions bound to the other hosts at the multi-function device.