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Method for the allocation of PCI/PCI-X memory resources with variable granularity

IP.com Disclosure Number: IPCOM000011744D
Publication Date: 2003-Mar-12
Document File: 3 page(s) / 71K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for the allocation of PCI/PCI-X memory resources with variable granularity. Benefits include improved functionality and improved performance.

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Method for the allocation of PCI/PCI-X memory resources with variable granularity 

                           

                           

Disclosed is a method for the allocation of PCI/PCI-X memory resources with variable granularity. Benefits include improved functionality and improved performance.

Background

                            PCI and PCI-X architectures allow for allocation of memory resources to PCI and PCI-X compliant devices in the system. System initialization software, such as the BIOS on a 32-bit architecture system, is responsible for assigning these memory resources. They are allocated in multiples of 4 KB on a boundary identical to the 4-KB multiple.

Description

              The disclosed method is the allocation of PCI/PCI-X memory resources with variable granularity. Resource allocation can occur in 1-KB or 4-KB granularity, provided the memory controller hub (MCH) has the capability (see Figure 1).

              Some operating systems (OSs) support this capability and can allocate memory space in a more optimal manner. For example, a PCI device may only require 256 bytes of memory for operation. If the system BIOS and OS can allocate 1 KB to the device, 3 KB of space is saved (see Figure 2).

              As a solution, the system BIOS can:

•             Determine which devices require 1 KB of memory space or less

•             Assign 1 KB of memory space

•             Align those 1 KB blocks contiguously for the optimal use of space

Advantages

              The disclosed method provides advantages, including:                                                                             

•             Improved functionality due to the allocation of PCI/PCI-X memory resources with variable granularity

•             I...