Microsoft KB Archive/817027

= FIX: Systems that have Intel Hyper-Threading technology installed and later disabled may not enter the ACPI C1 processor idle sleep state =

Article ID: 817027

Article Last Modified on 8/29/2007

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APPLIES TO


 * Microsoft Windows XP Professional
 * Microsoft Windows XP Professional
 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Home Edition

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SYMPTOMS
Systems that are based on Intel processors that have Hyper-Threading Technology (HTT) capability but that are running with Hyper-Threading disabled in the BIOS will not enter the Advanced Configuration and Power Interface (ACPI) C1 processor idle state.

This behavior may result in a higher operating temperature in the CPU.



Service pack information
To resolve this problem, obtain the latest service pack for Microsoft Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

322389 How to obtain the latest Windows XP service pack

Hotfix information
A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

For x86-Based Systems
  Date         Time   Version      Size    File name 27-06-2003 21:38 5.1.2600.1240 1,896,448  Ntkrnlmp.exe 27-06-2003 21:38 5.1.2600.1240 1,952,256  Ntkrnlpa.exe 27-06-2003 21:38 5.1.2600.1240 1,924,096  Ntkrpamp.exe 27-06-2003 21:38 5.1.2600.1240 1,928,960  Ntoskrnl.exe

For ia64-Based Systems
  Date         Time   Version      Size    File name -  27-06-2003  21:38 5.1.2600.1240 5,827,840  Ntkrnlmp.exe 27-06-2003 21:38 5.1.2600.1240 5,738,368  Ntoskrnl.exe



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section. This problem was first corrected in Microsoft Windows XP Service Pack 2.



MORE INFORMATION
Systems that have HTT appear to the operating system as Multi-Processor (MP) systems. The following sequence of events describes how the symptoms might occur:
 * 1) During installation on a system where HTT is enabled, Windows correctly chooses the MP kernel and Hardware Abstraction Layer (HAL).
 * 2) The processor driver is called by the Windows kernel power manager to invoke the C-state entry handler when the system is idle.

The processor driver is responsible for support of processor power management features, including ACPI C-state support.
 * 1) When HTT is later disabled, the system runs as a Uni-Processor (UP) system, but continues to use the MP kernel and HAL.
 * 2) On UP systems that have only one C-state available, the HAL C-state handler is used instead of the processor driver C-state handlers.

This issue occurs when you run a single processor on a system that has only C1 support with the multiprocessor kernel.

Keywords: kbhotfixserver kbqfe kbqfe kbwinxpsp2fix kbwinxppresp2fix kbfix kbbug KB817027

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