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Browse Prior Art Database

Method of optimizing memory space utilized by Open Firmware for storing device tree properties

IP.com Disclosure Number: IPCOM000181465D
Original Publication Date: 2009-Apr-02
Included in the Prior Art Database: 2009-Apr-02
Document File: 4 page(s) / 28K

Publishing Venue

IBM

Abstract

For adapters with the same vendor and device id, the device tree properties and methods that are created will be exactly the same. This new invention uses this concept to introduce a new method of saving common device tree properties and methods for adapters with the same device and vendor id. The new method will reduce the amount of memory space used to store the data when there are multiple adapters in the system with the same vendor and device id.

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Method of optimizing memory space utilized by Open Firmware for storing device tree properties

This disclosure provides a new method of optimizing memory space when storing device node properties and methods in NVRAM by Open Firmware.

In prior art invention, a limited probe process to optimize boot-time by not loading the device boot code at the time of probe is described. The prior art method uses a saved copy of the device tree during the probe process to obtain properties and methods that would have been created by the device driver code. In the prior art, the complete device tree created during the probe process is stored in memory. If there are multiple instances of the same adapter in the system, then the methods and properties for each will be stored in memory, creating a larger memory footprint.

This new invention is an improved method of how the data (which includes the methods and properties) specific to each adapter is stored in memory, providing an optimized use of the memory space.

When a system is first booted, or when the system is set to slow boot mode, the probe process will include the loading of the device drivers which will create the device tree properties and methods for each adapter. During the probe process, when an adapter is found, its properties and methods will only be stored in NVRAM if there does not already exist properties and methods in NVRAM for an adapter with the same vendor and device id. In this way, only a single copy of the properties and methods for an adapter with a specific vendor and device id will be stored in memory, reducing the amount of space that would be used if there are multiple adapters with the same information.

During hyperboot, when an adapter is found during the probe process, a check will first be made to see if there exist in NVRAM properties and methods for a matching device and vendor id. If the current adapters vendor and device id match the stored one, the properties and methods will be copied from NVRAM and used for the current device's node in the device tree. When data is copied from NVRAM for the specific adapter, the data in NVRAM needs to b...