PCIe Tunnel Hoisted Identifiers for Bus Number Conservation
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Solution Overview
Problem
The PCIe standard faces challenges in managing bus numbers for downstream devices connected via non-PCIe links, leading to compatibility issues and limited system expansion due to the exhaustion of available bus numbers, causing systems to either ignore new devices or re-run configuration processes.
Innovation Solution
The implementation of hoisted identifiers, which use a common bus number concatenated with an unassigned function number for packet routing, allows for the conservation of bus numbers and enables more devices to connect dynamically without requiring new system configurations, utilizing the 'white space' in function numbers with Alternative Routing-ID Interpretation (ARI) support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the root complex assigns bus numbers to downstream devices via non-PCIe links, then device connectivity is enabled, but the pool of available bus numbers is exhausted, causing system expansion to fail
Solution Approach 1:
The patent transitions from using only bus numbers for device identification to using a two-dimensional identifier system combining bus numbers with function numbers. This dimensional expansion allows the system to distinguish between multiple devices on the same bus number, effectively increasing the addressing capacity without consuming additional bus number resources.
Solution Approach 2:
The patent segments the device identification process into two independent components: bus number (first dimension) and function number (second dimension). By separating these identification functions, the system can reuse bus numbers across different function number ranges, thereby extending device connectivity while conserving the bus number pool.
2Adaptability or versatility
If the root complex assigns a range of bus numbers to accommodate downstream devices, then future device additions are enabled, but too many bus numbers are consumed, forcing reconfiguration when devices are added
Solution Approach 1:
The patent introduces dynamic device identification through function number assignment that can adapt to different device types and connection scenarios. The function number portion of the identifier can be dynamically assigned based on the specific device being connected, allowing the system to accommodate new devices without triggering a complete reconfiguration of the bus number scheme.
3Adaptability or versatility
If tunnels convert PCIe packets to non-PCIe packets for wireless communication, then protocol compatibility is achieved, but system configuration complexity increases
Solution Approach 1:
The patent introduces tunnels as intermediary components that bridge PCIe and non-PCIe protocols. These tunnels automatically handle packet format conversion between the two protocols, shielding the complexity of protocol translation from the configuration process and enabling seamless connectivity between PCIe devices and wireless networks without manual intervention.
Data Source
AI summary
A tunnel for a communication system includes first and second bridges. The first bridge has a first port adapted to couple to a first link and a second port, and has a first programmable bus number and a first programmable function number. The second bridge has a first port coupled to the second port of the first bridge, and a second port, and has a second programmable bus number and a second programmable function number. In a hoist enabled mode, the first bridge forwards a packet on the first link to the second bridge if the second programmable bus number is equal to the first programmable bus number, a bus number of the packet is equal to the first programmable bus number, and a function number of the packet is equal to the second programmable function number.