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Windows XP software updates (for example, security updates, critical updates, or hotfixes) that are released after Service Pack 1 (SP1) may include binary files for both Windows XP-based and Windows XP-based SP1 computers. These dual-mode update packages are designed to install post-SP1 updates on Windows XP-based computers regardless of whether they are running SP1. If you do not have SP1 installed, the dual-mode update also puts a post-SP1 version of the update on your computer, which is automatically installed if you install SP1. If you remove SP1, the pre-SP1 version of the update is restored. A new Update Migration tool (Xpsp1hfm.exe) determines which update to install and performs the migration.
Structure of dual-mode update packages
This is an example of the structure of a dual-mode update package:
\Sp1: This folder contains the files to apply to Windows XP-based computers that are not running SP1.
\Sp2: This folder contains the files to apply to Windows XP-based computers that are running SP1.
\Common: This folder contains installer files.
\Xpsp1hfm.exe: This folder contains the Dual-Mode Update Migration tool, which replaces Update.exe and which is initiated by the self-extracting Qnnnnnn_wxp_sp2_x86_enu.exe file.
Description of the Dual-Mode Update Migration tool
The Dual-Mode Update Migration tool (Xpsp1hfm.exe) performs the following tasks:
It installs itself in the %SystemRoot%\System32 folder.
It rearranges the extracted update files so that Update.exe can install the appropriate version.
It migrates previously installed dual-mode updates to the post-SP1 version when SP1 is installed.
It rolls the binaries back to the pre-SP1 version if SP1 is removed.
For example, if you install a dual-mode update on a Windows XP-based computer that is not running SP1, Xpsp1hfm.exe copies the post-SP1 update binaries to %SystemRoot%\$xpsp1hfm$\Qnnnnnn (where nnnnnn is the Microsoft Knowledge Base article number that is associated with the update), and then runs Update.exe from the temporary SP1 folder to install the pre-SP1 update. When you install a dual-mode update on a Windows XP-based computer that is running SP1, Xpsp1hfm.exe runs Update.exe from the temporary SP2 folder to install the post-SP1 update.
When you install SP1 on a Windows XP-based computer, the SP1 installation process runs Xpsp1hfm.exe to migrate any installed dual-mode updates to the appropriate post-SP1 version, and then configures the computer so that these updates are removed if you remove SP1 in the future. Xpsp1hfm.exe logs an event ID message to the Event log to indicate if the migration is the successful.
Note You cannot use the Add or Remove Programs tool in Control Panel to remove updates that are migrated in this way. Also note that the Qfecheck tool (Qfecheck.exe) may report that the same update is installed two times in this case. You can ignore this behavior because it does not indicate a problem with installed updates.
If you reinstall SP1, Xpsp1hfm.exe tries to migrate any updates that did not migrate during the first installation.
When you remove SP1, the removal process first calls Xpsp1hfm.exe to remove migrated dual-mode updates and revert your computer back to a state in which SP1 can safely be removed. The dual-mode updates can be removed at this point. An event ID message is logged to the Event log that indicates whether the migrated dual-mode updates were removed in this case.
For information about how to create a combination installation share to install Windows XP with the service pack and updates, see the "Update Installation and Deployment Guide" topic (the Hfdeploy.htm file) in the Support\Tools folder on service pack CD-ROM. Note that because dual-mode update packages include two sets of binary files, you must copy the files from the correct folder to the I386 folder when you prepare the combination installation. If you create a combination share with Windows XP and some dual-mode updates, you must copy the catalog and the files from the SP1 folder to the I386 folder. If you create a combination share with Windows XP, Service Pack 1, and some dual-mode updates, you must copy the catalog and files from the SP2 folder to the I386 folder.
For additional information about software updates, click the following article number to view the article in the Microsoft Knowledge Base:
824994 Description of the contents of a Windows Server 2003 product update package
Microsoft Windows XP Professional x64 Edition, Microsoft Windows XP Professional, Microsoft Windows XP Home Edition, Microsoft Windows XP Tablet PC Edition, Microsoft Windows XP Media Center Edition 2005 Update Rollup 2