Microsoft KB Archive/830987

= Some Devices Are Not Recognized When You Use Multiple IEEE 1394 (FireWire) Devices =

Article ID: 830987

Article Last Modified on 11/4/2007

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APPLIES TO


 * Microsoft Windows Server 2003, Web Edition
 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
 * Microsoft Windows Server 2003, Enterprise x64 Edition
 * Microsoft Windows XP Professional
 * Microsoft Windows XP Home Edition

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SYMPTOMS
If you have multiple devices on the same computer that use the Institute of Electrical and Electronic Engineers (IEEE) 1394 high-speed serial bus (alternatively known as FireWire), some of the devices may not be recognized correctly.

When you use only one of these devices, Plug and Play loads the correct driver and the device works correctly. However, if you use two IEEE 1394 devices on your computer, the driver is not called a second time. Therefore, only the first device is recognized.



CAUSE
This problem may occur if the device IDs for the IEEE 1394 devices are similar. For example, this problem may occur if the first device has a unique ID (UID) of 200000002A30B00 and the second device has a UID of 210000001A30B00.

The 1394 device enumerator (1394bus.sys) has a device table that is implemented as a hash table that is stored in an array. The hash function calculates a hash based on the UID of the device. If there is a collision (if the hash values that are calculated for each device are the same), a larger table is allocated.

If two device IDs are similar, the hash calculation produces the same value for both devices. Therefore, a collision occurs and the code continually reallocates larger arrays up to the table size limit. Because the hash table reaches its size limit before the new entry for the second device is added to the table, the second device is not recognized.



Hotfix Information
To resolve this problem, obtain the latest service pack for Windows XP. For more 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

Prerequisites
To apply this hotfix, you must have Windows XP Service Pack 1 (SP1) installed.

Restart requirement
You must restart your computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
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.

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 Windows Server 2003 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

Prerequisites
No prerequisites are required.

Restart Requirement
You must restart your computer after you apply this hotfix.

Hotfix Replacement Information
This hotfix does not replace any other hotfixes.

File information
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.

Windows Server 2003, x86-based versions


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
After you install this hotfix, a hash calculation that has higher entropy is used for the device table. This behavior prevents the collisions that may occur if the IEEE 1394 device IDs are similar.

For more information about IEEE 1394 technology, visit the following Microsoft Web site:

http://www.microsoft.com/whdc/system/bus/1394/default.mspx

For additional information about using IEEE 1394 devices with Windows XP, click the following article number to view the article in the Microsoft Knowledge Base:

310433 Using IEEE (FireWire) Devices with Windows XP

For additional information about how hotfix packages are named, click the following article number to view the article in the Microsoft Knowledge Base:

816915 New Naming Schema for Microsoft Windows Hotfix Packages

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the Standard Terminology That Is Used to Describe Microsoft Software Updates

Keywords: kbbug kbfix kbqfe kbhardware kbwinxpsp2fix kbwinxppresp2fix kbwinserv2003presp1fix kbhotfixserver KB830987

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