Virtual Expansion ROM in PCIe Hierarchy
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Solution Overview
Problem
Existing PCIe systems lack the ability to efficiently manage and present a virtual Expansion ROM hierarchy to hosts, limiting flexibility and control in boot processes and device management.
Innovation Solution
A management device capable of detecting and modifying PCIe hierarchies to add a virtual Expansion ROM, which receives and services host requests by providing boot instructions from internal memory, while masking its presence from the host.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a management device directly presents itself in the PCIe hierarchy to hosts, then it can provide boot instructions and manage devices, but it compromises security and control by exposing its presence to the host system
Solution Approach 1:
The patent introduces a management device that operates as an intermediary in the PCIe hierarchy, allowing it to service boot requests and manage devices without the host needing to directly interact with or be aware of the management device's internal operations. The management device intercepts and handles requests that would otherwise need to go to a physical Expansion ROM, thereby masking its presence while maintaining full functionality.
Solution Approach 2:
The patent creates a virtual Expansion ROM that replicates the functionality of a physical Expansion ROM without requiring the actual hardware to be present or accessible to the host. This virtual copy allows the management device to provide boot instructions and device management capabilities while remaining hidden from the host system, resolving the contradiction between security and operational capability.
2Adaptability or versatility
If physical Expansion ROM hardware is used in PCIe devices, then boot instructions can be provided to hosts, but the system lacks flexibility and the management device's presence must be exposed to the host
Solution Approach 1:
The patent replaces the mechanical/physical Expansion ROM hardware with a virtual implementation managed by software or firmware in the management device. This substitution eliminates the need for physical ROM chips in each PCIe device, providing greater flexibility in how boot instructions are stored and delivered while simplifying the overall system architecture by removing redundant physical components.
Solution Approach 2:
The management device serves multiple functions: it acts as a virtual Expansion ROM for boot instructions, a device manager for PCIe devices, and a security layer that masks its presence from hosts. This multi-functionality increases adaptability while the virtual nature of the Expansion ROM reduces physical device complexity compared to having dedicated Expansion ROM hardware in each PCIe device.
3Reliability
If the management device masks its presence from the host, then security and control are improved, but the host cannot directly access boot instructions without the virtual Expansion ROM intermediary
Solution Approach 1:
The management device performs preliminary actions by intercepting boot requests early in the boot process and redirecting them to the virtual Expansion ROM. This allows boot instructions to be delivered efficiently without requiring the host to wait for or directly access the management device, maintaining security while minimizing any potential time loss in the boot process.
Data Source
AI summary
Methods and structure for utilizing a virtual Expansion ROM. One exemplary embodiment is a management device. The management device includes a memory, a Peripheral Component Interconnect Express (PCIe) link, and a processor. The memory stores Expansion Read-Only Memory (Expansion ROM) boot instructions for a host. The processor identifies devices in a PCIe hierarchy by transmitting PCIe enumeration requests via the PCIe link. The processor also generates a synthetic PCIe hierarchy that includes an added virtual Expansion ROM which is not present in the PCIe hierarchy, and provides responses describing the synthetic PCIe hierarchy to a host. Furthermore, the processor acquires PCIe read requests initiated by the host that are directed to the virtual Expansion ROM, and provides boot instructions to the host from the memory based on the PCIe read requests.