Bus Extension Unit for Remote Device Connection Management
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Solution Overview
Problem
In computer systems combining pass-through technology and bus extension technology, there is a challenge in designating remote devices when some remote devices are not started up, leading to potential misassignment of device control between guest OSes.
Innovation Solution
A computer system with a bus extending unit that constructs a virtual bus to remote devices via a network, using a communication controlling unit to manage correspondence between guest OSes and remote devices using identification information that remains constant regardless of device start-up states, ensuring accurate device designation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bus extension technology is used to connect guest OSes to remote devices via network, then device accessibility is improved, but device misassignment occurs when remote devices are not started up
Solution Approach 1:
The patent applies preliminary action by pre-assigning fixed BDF (Bus Device Function) numbers to each remote device before the system starts up. The host OS configures the correspondence between guest OSes and remote devices in advance, storing this mapping information. When a guest OS needs to access a remote device, it uses the pre-configured BDF number to directly identify the target device, avoiding the need to scan and dynamically assign devices at runtime. This ensures that even if some remote devices are not started up, the BDF numbers remain valid and uniquely identify the intended devices, preventing misassignment.
2Adaptability or versatility
If dynamic device scanning is performed at start-up, then device availability is improved, but device designation becomes unstable when configuration changes
Solution Approach 1:
The patent performs device scanning and BDF assignment as a preliminary action during system initialization, but then maintains stable, fixed BDF assignments rather than re-scanning dynamically. The host OS stores the mapping between guest OSes and remote devices in a configuration file or database, preserving these assignments across reboots. This approach ensures device availability is established at startup while maintaining designation stability during subsequent operations, even when the physical configuration changes.
Solution Approach 2:
The patent creates a virtual copy of the device mapping information in the form of BDF numbers and correspondence tables. Instead of directly referencing physical device states, the system uses these virtual representations to manage device access. The BDF numbers serve as stable virtual identifiers that map to physical devices, allowing the system to maintain stable device designations even when physical device availability changes, as long as the virtual mapping information is preserved.
Data Source
AI summary
This computer system improves the ease with which a guest OS and remote device can be connected in a configuration combining pass-through technology and bus extension technology. The computer system is provided with a bus extending means for constructing a virtual bus to one or more remote devices connected via a network, and an executing means for configuring a virtual hardware environment and executing a host operating system for causing a guest operating system to control the remote device(s). The bus extending means comprises a communication controlling means for consulting a management table for managing relationships of correspondence between the guest operating system and the remote device(s) by using identification information that does not change depending on the startup state of the remote device(s), and controlling communication between the guest operating system and the remote device(s).