PCIe Switch Firmware Booting for Multiple Hosts

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Solution Overview

Problem

Current information handling systems face challenges in booting multiple hosts from a shared PCIe device, as existing technologies restrict access to firmware code stored in expansion ROM, limiting the ability of virtual functions to utilize the functionality of SR-IOV endpoints.

Innovation Solution

A mechanism is implemented using a Multi-Root (MR) PCI Express (PCIe) manager and an MR I/O Virtualization (IOV) switch that stores expansion ROM firmware in non-volatile random access memory (NVRAM), allowing host systems to access the firmware code by trapping transactions and providing the base address, enabling multiple hosts to boot from a shared PCIe device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If expansion ROM firmware is restricted to single-host access, then device security and integrity are maintained, but multiple hosts cannot boot from the shared PCIe device

Engineering Contradiction:

Improvemulti-host boot capabilityVSAvoidfirmware access management

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent creates a copy of the expansion ROM firmware code in NVRAM on the IOV switch, allowing multiple hosts to access identical firmware images simultaneously. This copying mechanism enables virtual functions from different hosts to boot from the same PCIe device without direct access to the physical expansion ROM, resolving the contradiction between multi-host capability and access management complexity

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The IOV switch acts as an intermediary between hosts and the PCIe device, managing firmware access through transaction trapping and redirection. The switch intercepts firmware read requests from virtual functions and redirects them to stored firmware copies in NVRAM, eliminating the need for complex multi-host access protocols while maintaining security and integrity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If virtual functions can access expansion ROM directly, then boot functionality is enabled, but access conflicts occur when multiple hosts share the same PCIe device

Engineering Contradiction:

Improveboot operationVSAvoidfirmware access reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system performs preliminary action by pre-loading firmware images from the expansion ROM into NVRAM on the IOV switch during system initialization. This advance copying ensures that when multiple hosts attempt to boot simultaneously, each host receives firmware from its own pre-loaded copy in NVRAM, eliminating access conflicts and ensuring reliable boot operations for all hosts

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The IOV switch serves as an intermediary that traps firmware access transactions from virtual functions and redirects them to appropriate firmware copies in NVRAM. This mediation layer prevents direct access conflicts between multiple hosts while maintaining the appearance of direct firmware access, ensuring both ease of operation and reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10146718B2Mechanism to boot multiple hosts from a shared PCIe device

Publication Date: 2018.12.04 DELL PROD LP

AI summary

A PCIe switch including a memory and a processor. The processor is operable to receive a transaction from an information handling system to an endpoint device, determine that the transaction is a request to receive firmware code from the endpoint device, block the transaction from being issued to the endpoint device, and provide the firmware code to the information handling system from the memory.