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

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.

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.

Windows XP

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:

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.

Windows XP, Itanium-based versions

Windows XP, x86-based versions

Windows Server 2003

Hotfix Information

A supported hotfix is 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 software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if 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. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

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, Itanium-based versions

Windows Server 2003, x86-based versions

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

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