PCIe Host Bridge Virtual Interrupt Mode Interface
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Solution Overview
Problem
Newer PCIe-based devices often fail to function correctly in older computer systems due to lack of support for older PCI interrupt modes, leading to incompatibility issues between newer and older technology components.
Innovation Solution
A virtual interrupt-mode interface is introduced in a PCIe switch or host bridge to provide a virtual older-technology-interrupt-mode interface to operating systems and BIOS layers, allowing newer devices to emulate older interrupt modes, such as INTx, even if they only support MSI and MSI-X interrupts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If newer PCIe-based devices are used to replace older PCI devices, then data transfer bandwidth and system performance are improved, but compatibility with older systems relying on PCI interrupt modes deteriorates
Solution Approach 1:
The patent introduces a host bridge as an intermediary component between the PCIe device and the older PCI-based system. The host bridge translates modern PCIe interrupt modes (MSI/MSI-X) into legacy PCI interrupt modes (INTx), enabling compatibility without requiring modifications to either the newer PCIe device or the older system infrastructure. This mediator resolves the contradiction by allowing high-speed PCIe communication while maintaining backward compatibility with older interrupt handling mechanisms.
2Productivity
If newer PCIe devices that only support MSI and MSI-X interrupts are deployed, then device functionality and efficiency are improved, but interoperability with operating systems and BIOS layers designed for older interrupt modes deteriorates
Solution Approach 1:
The host bridge dynamically changes the interrupt mode parameter based on the capabilities of the connected device and the requirements of the system software. When a PCIe device using MSI or MSI-X interrupts is detected, the host bridge translates these interrupt modes into the older INTx format that legacy operating systems and BIOS layers expect. This parameter transformation maintains device efficiency while ensuring reliable interoperability with legacy software environments.
3Reliability
If parallel bus architectures are replaced with serial communications media, then signal integrity and ease of incorporation are improved, but backwards compatibility with parallel bus components deteriorates
Solution Approach 1:
The patent segments the communication interface into distinct layers: the physical serial PCIe layer and the logical parallel PCI layer. The host bridge acts as a boundary between these segments, handling protocol translation and interrupt mode conversion. This segmentation allows the system to benefit from the signal integrity and ease of incorporation of serial communications while maintaining backwards compatibility with parallel bus components through the translation layer.
Data Source
AI summary
Embodiments of the present invention are directed to methods for virtualizing interrupt modes on behalf of interrupt-generating devices, including I/O-device controllers, so that newer interrupt-generating devices that lack older interrupt modes can be used in systems that continue to rely on older interrupt modes. In one embodiment of the present invention, a PCIe switch or PCIe-based host bridge is modified, or a new component introduced, to provide an interrupt-mode virtualizing function, or virtual interrupt-mode interface, that provides a virtual interrupt mode on behalf of interrupt-generating devices, such as I/O-device controllers, to operating systems, BIOS layers, and other components that communicate with the I/O-device controllers.