Operating system support for hot-add memory in Windows Server

Updated: October 28, 2010

This topic discusses operating system support for hot-add memory in Windows Server.

This information applies to:

  • Windows Server 2008 R2, Enterprise Edition and Datacenter Edition
  • Windows Server 2008, Enterprise Edition and Datacenter Edition
  • Windows Server 2003, Enterprise Edition and Datacenter Edition

Operating system support for hot-add memory consists of the following:

  • Support for the memory device object as described in Section 10.12 of the ACPI 2.0 Specification and in this article.
  • A system-supplied kernel-mode driver for ACPI 2.0 memory device objects that describes the memory ranges contained in the objects to the Memory Manager.
  • Changes to the Memory Manager to support dynamic addition of memory to a running system.
  • Use of the Static Resource Affinity Table (SRAT) to determine the amount and ranges of hot-add memory and to determine whether to enable PAE on x86-based platforms when hot-add memory has addresses over 4GB.

When memory is hot-added to the system, the following steps occur:

  1. The ACPI BIOS generates an ACPI Notify(1) (device check) to the memory device object that describes the hot-added memory.
  2. The operating system re-evaluates the _STA method on the memory device object to determine if it now claims that the memory is present.
  3. If the memory is present, the Plug and Play subsystem loads the system-supplied driver for memory device objects.
  4. This memory device object driver informs the Memory Manager about the new memory ranges.
  5. The Memory Manager makes the new memory available to the operating system, drivers, and applications.

Related topics

Hot-Add Memory Support in Windows Server
Static Resource Affinity Table
ACPI 2.0 Specification

 

 

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