ACPI Table Property Name Underscore Repositioning
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Solution Overview
Problem
Existing operating systems face challenges in efficiently managing device properties in ACPI tables, particularly in updating property names without altering checksums, which is crucial for indicating unsupported properties without compromising table integrity.
Innovation Solution
The system modifies device property names in ACPI tables by moving the underscore character from the beginning to the end of the property name, ensuring that the checksum remains unchanged, allowing for efficient runtime updates that indicate unsupported properties without requiring changes to the checksum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If device property names are modified in ACPI tables to indicate unsupported properties, then the ability to dynamically manage device properties is improved, but the checksum validation requirement creates complexity in maintaining table integrity
Solution Approach 1:
The patent changes the parameter being modified from the entire property name string to specifically the underscore character position within the property name. By moving the underscore from the beginning to the end of the property name string, the system achieves runtime property disabling while maintaining checksum validity, as this specific parameter change approach preserves the overall string hash characteristics.
Solution Approach 2:
Instead of modifying entire property names or implementing complex checksum recalculation mechanisms, the patent applies a partial action by only repositioning the underscore character. This minimal modification approach is sufficient to indicate unsupported properties while avoiding the need for full checksum recalibration, thus reducing the complexity burden.
2Speed
If property names are updated at runtime to indicate unsupported device properties, then the responsiveness of the system is improved, but the requirement to maintain checksum integrity increases operational complexity
Solution Approach 1:
The patent modifies a specific parameter (underscore position) rather than the entire property name, enabling rapid runtime updates. This parameter-level change approach allows the system to quickly indicate unsupported properties without triggering complex checksum validation routines, thus maintaining both speed and simplicity.
Solution Approach 2:
The property name is segmented into components, with the underscore character treated as a separate modifiable element. This segmentation allows the system to modify only the necessary portion (underscore position) to convey property support status, enabling fast runtime updates while preserving the rest of the property name structure and its associated checksum characteristics.
3Ease of operation
If a single atomic memory operation is used to enable or disable device properties, then the ease of operation is improved, but the need to maintain checksum invariance creates a constraint on the modification approach
Solution Approach 1:
The patent identifies a specific parameter (underscore character position) that can be changed via a single atomic memory operation. By focusing modification efforts on this specific parameter rather than the entire property name, the system achieves both operational simplicity and checksum invariance, as the localized change maintains the overall string hash properties.
Solution Approach 2:
The property name structure serves its own integrity function through the underscore repositioning mechanism. The modified property name format (with underscore at the end) inherently signals unsupported properties while maintaining checksum validity, eliminating the need for separate checksum verification and modification routines.
Data Source
AI summary
A system and method are disclosed for efficient runtime modification of device property names in Advanced Configuration and Power Interface (ACPI) tables. In accordance with one embodiment, a computer system determines whether a device supports a device property, and when the device does not support the device property, a device property name corresponding to the device name is modified in a particular entry of an ACPI table, such that a checksum for that entry remains unchanged. The modified device property name indicates to the computer system that the device does not support the device property.